The new map suggests that the plateaus around the Venera landers could be made of granite, which on Earth is formed by shifting continents.

The map is made up of more than 1000 individual images, taken during night-time orbits between May 2006 and December 2007. It combines temperature data from Venus Express's VIRTIS (Visible and Infrared Thermal Imaging Spectrometer) instrument with topographical data from NASA's Magellan probe to show that different regions of the planet have different temperatures. The mountains are cooler (blue, around 422 °C) and the plains are warmer (red, around 442 °C).

Rocks absorb heat during the day, and radiate it back out after the sun sets. Different materials, like granite or basalt, radiate at different temperatures, which allows researchers to distinguish between them.

The new map is "really clever and really new", says planetary scientist Mark Bullock of the Southwest Research Institute in Boulder, Colorado. "There are real differences in brightness that almost certainly have to do with compositional differences of the rocks." (Illustration: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA)